In an attempt to increase the fuel efficiency and reduce an emission of scavenging two-stroke engines, it is known to direct fresh air from an airline to the top end of the transfer, or scavenging, ducts during regular engine operations. The fresh air acts as a buffer between the combustion gasses that are to be exhausted and the fuel and air mixture that is initially directed into the crankcase from the fuel and air inlet channel, which ultimately enters the combustion chamber through the scavenger ducts in preparation for the subsequent combustion event. In short, the fresh air directed to the scavenger ducts is first to enter the combustion chamber as the piston moves from the top dead center position to the bottom dead center position, rather than the fuel and air mixture from the crankcase. As such, any initial mixing that may occur in the combustion chamber with the combustion gasses is with the fresh air from the scavenger ducts rather than the fuel and air mixture. This improves fuel efficiency as the amount of any unspent fuel that may exit the combustion chamber with the combustion gasses during the exhaust operations due to mixing is reduced. However, the introduction of fresh air into the scavenger ducts during normal operations also means that during start-up, the combustion chamber initially receives fresh air from the scavenger ducts rather than the fuel and air mixture from the crankcase. As such, the fuel and air mixture that is provided to the combustion chamber during start-up of the engine will be leaner than desired for efficient engine start-up. As such, the operation of such two-stroke combustion engines is often complicated by the use of a choke, as is known, at start-up to make the fuel and air mixture temporarily richer. Those issues are typically encountered in those two-stroke engines having independent fresh air and fuel and air mixture channels. Alternatively, an operator has to pull a starting rope a number of times (at least 3-4 times at a cold start of the engine) to allow a sufficient amount of the fuel and air mixture from the crank house via the scavenging channels to reach the combustion chamber in a such concentration of fuel that would be enough for the ignition. Therefore, it is desirable to have a two-stroke engine in which easier and quicker to start, especially for the cold start, that allows to create a richer and easier to ignite the fuel and air mixture concentration in the combustion chamber at the engine start, although fresh air is provided to the scavenging ducts during normal operations, the fresh air might not be provided during the engine start-up.
The present invention recognizes and addresses considerations of prior art constructions and methods.